Two-stage pump



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/4//0/1 6. J/lep oard j ATTO/PA/EVJ Patented Apr. 27, 1948 TWO-STAGEPUMP Allan G. Sheppard, Elmira, N. Y., minor to American-LaFrance-Foamlte Corporation, Elmira, N. Y., -a corporation of New YorkApplication November 21, 1946, Serial No. 212,632

6 Claims. 1

v This invention relates to water pumps of the appropriate for firedepartment use and has for its primary object the provision of animproved multi-stage pump of high efliciency and so organized as to bequickly convertible from series to parallel stage operation.

With the foregoing and other objects in view, as will hereinafterappear, the invention comprises the devices, combinations andarrangements of parts hereinafter set forth and illustrated in theaccompanying drawings of a preferred embodiment of the invention, fromwhich the several features of the invention and the advantages attainedthereby will be readily understood by those skilled in the art.

In the drawings:

Fig. 1 is an elevation of a preferred form of pump acording to theinvention;

Fig. 2 is a top plan view, partially broken out and sectioned;

Fig. 3 is a section on the line III--III of Fig. 1;

Figs. 4 and 5 are sectional views on the lines IV-IV and V--V,respectively, of Fig. 2; and

Fig. 6 is a section on the lines VI--VI of Fig. 2.

In the illustrated embodiment, and as is preferred, the pump includes amain housing of elongated form appropriate for mounting transverselyupon a truck chassis with the water inlets 2 and 3 located at oppositeends of the housing so that either one may :be conveniently hose-coupledto the water supply source for the P mp.

Within the housing, and cast integrally with it, for example, are twocasings, generally designated 4 and 5, in which are mounted first andsecond stage impellers B and 1, respectively. The impellers are securedto a common shaft 8 which may be journaled at its ends in the hous ingside walls 9 and I0.

The casings 4 and 5 are spaced from each other and from the housing sidewalls so that, with their wall extensions I, l2, l3, and I4, theyconstitute partitions extending throughout the major portion of thelength of the housing and provide intervening spaces l5, l6 and II. Thelatter may conveniently be designated water inlet spaces, all three ofthem opening at their opposite ends into the end portions of thehousingsupplied by the water inlets 2 and -3. For convenience, the designationsfirst and secand are sometimes used herein to identity the spaces,passages and so forth, associated with the first and second stage units,respectively.

The first stage unit is of a dual inlet type and, in this instance,though of the same diameter,

is of double the capacity of the second stage unit, which is of a singleinlet type. As indicated, the first stage unit incorporates dual inletsI8, I! on opposite sides of the casing 4 and communicating with thefirst stage inlet spaces It and I6, respectively; and the second stageunit incorporates a single inlet 20 communicating with the first stageinlet space H. As shown particularly in Figs. 4 and 5, the first andsecond stage casings are provided with discharge-passages 2| and 22,respectively, and valve means are provided whereby the two units may .beconnected, in series or in parallel, to a discharge header 23 to supplya number of hose outlets 24, 25.

To control the coupling of the units to the header there is provided amanually operable valve the construction and operation of which will beapparent from Figs. 2 and 4 of the draw- 20 ings. In the positionillustrated in Fig. 4, the

head 28 (constituting the valve proper) occupies its extreme left handposition abutting a seat 21 and the discharge from the first stage unitflows through passage 2| into header 23 as indicated by the full-linearrow. The second stage unit likewise (and at all times) will bedischarging directly into the header by way of passage 22. In otherwords, the units are coupled in parallel.

To convert to series operation the valve-2B is withdrawn by handwheel 28to its extreme right hand position abutting a seat 29, thereby shuttingoil the first stage discharge passage 2| from direct communication withheader 23. The valve 28 is shown so positioned in Fig. 2. As the valveis thus withdrawn from seat- 21 it opens a port 30 and provides anoutlet from discharge passage 2| into a passage 3|, as indicated by thebroken-line arrow in Fig. 4. As appears in Figs. 2 and 3 the passage 3|discharges into the second stage inlet space H.

To complete the conversion to series operation, means are provided forclosing off the second stage inlet space from the housing, so that thesecond stage supply is derived solely from the first stage discharge (byway of passage 3|, as above described). Such means is preferablyautomatic in the sense of requiring nothing more of the operator thanthe manipulation of hand wheel 28, and, as shown, may comprise a pair offlow-controlled, hinged valves 32, 33. As will be understood, thesevalves will be moved to and held in their open position during paralleloperation of the units, as a result of the inflow of water from thehousing and throughinlet space H to the second stage inlet 20; whereaswhen the units are coupled in series in the manner described, the valveswill be moved to and held in their closed position by the greater fiow(representing the discharge from the larger capacity first stage unit)which enters space I! from passage 3 I In addition to the structuraladvantages inherent in the described form and the hydraulic balanceeffected by the described arrangement of the impellers, the inventionlends itself to more eflicient operation than can lie-achieved by any ofthe customary two stage or four stage pump arrangements. For instance,the impellers may be designed so that when pumping in parallel,approximately 70% of capacity is taken through the double suction firststage and the 30% balance through the single suction second stage. Thesetwo stages, representing substantially the practical equivalent of threeimpellers but without their complexity and space requirements, cansatisfy lift conditions not possible witha conventional two stage pump,can provide ample suction to deliver, say 1500 gallons per minute at 150p. s. i.; and, when converted to series operation, the double inletfirst stage impeller has ample suction capacity to ensure net deliveriesof 70% of capacity, or 1050 gallons per minute, at 200 p. s. i., and50%, or 750 gallons per minute at 250 p. s. 1. These capacities areavailable for delivery on a ten foot lift using two lengths of standardsix inch suction hose to supply the pump.

In the light of the foregoing description the following is claimed:

1. A two-stage, series-parallel pump comprising: an elongated housinghaving a water supply inlet at each end; first and second stage impellercasings mounted within the housing and laterally spaced from each otherand from the housing sidewalls to provide first stage inlet spacesbetween the first stage casing and its proximate housing side wall andbetween the casings, and a second stage inlet space between the secondstage casing and its proximate housing side wall, said three inletspaces all opening at their opposite ends into the end portions of thehousing; a. large capacity first stage impeller and a smaller capacitysecond stage impeller mounted in the respective casings and secured to acommon shaft journalled in the said housing side walls; dual casinginlets to the opposite sides of the first stage impeller communicatingwith said first stage inlet spaces, and a single casing inlet to thesecond stage impeller communicating with said second stage in-let space;a discharge header; a first discharge passage from the first stagecasing communicating with the header and with the second stage inletspace, and a second discharge passage from the second stage casing tothe header; a. manually operable valve movable to one position to directthe water flow in the first discharge passage to the header only and toanother position to direct such flow to the second stage inlet spaceonly; and valve means responsive to movement of the said manuallyoperable valve to its said positions, respectively, to open and to closeoff communication between the said end portions of the housing and thesecond stage inlet space.

2. A two-stage, series-parallel pump comprising: a housing; first andsecond stage impeller casings mounted within the housing and laterallyspaced from each other and from the housing side walls to provide firststage inlet spaces between Q a smaller capacity second stage impellermounted in the respective casings and secured to a common shaftjoumalied in the said housing side walls; dual casing inlets to theopposite sides of the first stage impeller communicating with said firststage inlet spaces, and a single casing inlet to the second stageimpeller communicating with said second stage inlet space; a dischargeheader; a first discharge passage from the first stage casingcommunicating with the header and with the second stage inlet space; anda second discharge passage from the second stage casing to the header; amanually operable valvemovable to one position to direct the water fiowin the first discharge passage to the header only and to anotherposition to direct such flow to the second stage ininlet' space only;and valve means responsive to movement of the said manually operablevalve to its said positions, respectively, to open and to close oifcommunication between the said portion of the housing and the secondstage inlet space.

3. A two-stage, series-parallel pump comprising; a housing; first andsecond stage impeller casings mounted within the housing and laterallyspaced from each other and from the housing side walls to provide firststage inlet spaces between the first stage casing and its proximatehousing side wall and between the casings, and a second stage inletspace between the second stage casing and its proximate housing sidewall; a water supply inlet to a portion of the housing normally incommunication with all three of said inlet spaces; a large capacityfirst stage impeller and a smaller capacity second stage impellermounted in the respective casings and secured to a common shaft; dualcasing inlets to the opposite sides of the first stage impellercommunicating with said first stage inlet spaces, and a single casinginlet to the second stage impeller communicating with said second stageinlet space; a discharge header; a first discharge passage from thefirst stage casing communicating with the header and with the secondstage inlet space, and a second discharge passage from the second stagecasing to the header; a manually operable valve movable to one positionto direct the water fiow in the first discharge passage to the headeronly and to another position to direct such flow to the second stageinlet space only; and valve means movable to open and to close oilcommunication between the said portion of the housing and the secondstage inlet space.

4. A two-stage, series-parallel pump comprising: a housing; first andsecond stage impeller casings mounted within the housing and laterallyspaced from each other and from the housing side walls to provide firststage inlet spaces between the first stage casing and its proximatehousing side wall and between the casings, and a second stage inletspace between the second stage first stage impeller communicating withsaid firststage inlet spaces, and a single casing inlet to the secondstage impeller communicating with said second stage inlet space; adischarge header; a first discharge passage from the first stage casingcommunicating with the header and with the second stage inlet space, anda second discharge passage from the second stage casing to the header;and valve means adapted for coupling the said casings and dischargepassages to the header in series or in parallel.

5. A two-stage, series-parallel pump comprising: a housing; first andsecond stage impeller casings mounted within the housing and, with thehousing, forming first and second stage inlet spaces; a water inlet tothe housing adapted to supply both said spaces; a large capacity firststage impeller and a smaller capacity second stage impeller mounted inthe respective casin'gs and secured to acomrnon shaft journalled in thesaid housing; a casing inlet to the first stage impeller communicatingwith said first stage inlet space, and a casing inlet to the secondstage impeller communicating with said second stage inlet space; adischarge header; a first discharge passage from the first stage casingcommunicating with the header and with the second stage inlet space,and'a second discharge passage from the second stage casing to theheader; a manually operable valve movable to one position tov direct thewater fiow in the first discharge passage to the header only and toanother position to direct such flow to the second stage inlet spaceonly; and valve means responsive to movement of the said manuallyoperable valve to its said position, respectively, to open and to close0d communication between the housing and the second stage inlet space.

6. A two-stage, series-parallel pump comprising: a housing; first andsecond stage impeller casings mounted within the housing and, with thehousing, forming first and second stage inlet spaces; a water inlet tothe housing adapted to supply both said spaces; a large capacity firststage impeller and a smaller capacity second stage impeller mounted inthe respective casings and secured to a common shaft; a casing inlet tothe first stage impeller communicating with said first stage inletspace, and a casing inlet to the second stage impeller communicatingwith said second stage inlet space; a discharge header; a firstdischarge passage from the first stage casing communicating with theheader and with the second stage inlet space, and a second dischargepassage from the second stage casing to the header; and valve meansadapted for cowpling the said casings and discharge passages to theheader in series or in parallel.

